Use of lasers for medical purposes is well established. Lasers are used extensively for cosmetic purposes such as hair removal, vein treatment, skin rejuvenation, treatment of telangeatesia and treatment of port wine stain. Each of these treatments is preferably performed with a laser producing laser pulses at a wavelength chosen to be most effective for the particular treatment. Some wavelengths are very preferentially absorbed in a particular type of tissue. Some wavelengths are highly absorbed in skin tissue with penetration depths of only a few microns. Other wavelengths have absorption coefficients substantially less than 1/cm and penetrate substantial depths in skin and other tissue. FIGS. 6 and 7 show absorption coefficients as a function of wavelengths for blood, human skin and melanin. A Nd:YAG laser operating at 1320 nm (with high absorption in skin tissue) may be used for skin rejuvenation and micro skin surgery. Treatment of port wine stains is usually performed using a dye laser operating at a wavelength of 577 nm where the absorption in blood is high. Another example is the 532 nm wavelength of frequency doubled YAG:Nd laser is widely used to treat vascular lesions like telangiectasia, or small facial veins. Though this laser light works well on small veins it does not perform so well on larger veins mainly because of high absorption of oxyhemoglobin in upper part of a vein. This creates a shield which prevents laser light from penetrating deeper to the lower part of the vein. As a result larger veins are coagulated non-uniformly and vein destruction of the larger veins is not satisfactory.
Use of a laser beam matched to a peak or relatively high absorption in tissue to treat the tissue is referred to as xe2x80x9cselective thermolysisxe2x80x9d. When wavelengths which penetrate deeply and are absorbed relatively uniformly in tissue are used to treat the tissue, the treatment is referred to as xe2x80x9cnon-selective thermolysisxe2x80x9d.
What is needed are enhancement of the selective thermolysis lasers and methods to improve results of medical and cosmetic treatment.
The present invention provides a laser system and process by which prior art medical and cosmetic laser techniques using laser beams chosen to produce selective thermolysis are enhanced by the addition of a second laser beam chosen for much deeper transmission in tissue and more uniform absorption. Preferred embodiments include enforcement with a 1079 nm YAP:Nd laser beam of a 532 nm beam produced by a frequency doubled YAG:Nd laser beam.